Defaults.Exposed › September 2026 census › v10 registry › Nameserver diversity
Nameserver diversity
Methodology v10 · canonical ID nameserver-diversity · DNS Security · scored · census as of September 5, 2026
Multiple independent nameservers so one outage doesn't take you offline.
Definition
| Canonical ID | nameserver-diversity |
|---|---|
| Category | DNS Security |
| Grade impact | Scored, counts toward the grade |
| Pass | The domain delegates to two or more nameservers with meaningful diversity. |
| Fail | A single nameserver (or no redundancy) serves the zone. |
| Example (passing) | NS: ns1.example-dns.com, ns2.example-dns.net |
No-data rule: when this check couldn't be determined for a domain (timeout, SERVFAIL, redacted source) it returns N/A and is excluded from that domain's scoring denominator: "couldn't determine" is never counted as a failure. "Determined absent" is a real fail.
Prevalence across the census
The public census rollup does not publish a per-check figure for nameserver-diversity (as of September 5, 2026).
Whole-census aggregates live at /v10/data; no number is shown here rather than an estimated one.
Census denominator: 316,600,902 graded domains. Aggregates only: never an individual domain's result.
Fix it
Plain-English impact, cost of ignoring it, and step-by-step remediation: defaults.exposed/fix/nameservers
Cite this check
Defaults.Exposed, "Nameserver diversity (nameserver-diversity)", Grading Methodology v10 (census as of September 5, 2026). https://defaults.exposed/v10/methodology/nameserver-diversity
Permalink: https://defaults.exposed/v10/methodology/nameserver-diversity ·
All 34 checks: v10 registry ·
Machine-readable: /v10/methodology/checks.json ·
Licence: open data